1. Field of the Invention
The present invention relates to bottom forming apparatuses for cartons. Specifically, the present invention relates to a bottom forming apparatus for a carton having portions of the bottom elevated to protect the raw paperboard edges from damage and absorption of moisture.
2. Description of the Related Art
Cartons fabricated from a carton blank on a form, fill and seal packaging machine risk absorption of moisture into the raw paperboard edges of the bottom of the carton. This absorption is accelerated if the raw paperboard edges are damaged and the carton is continuously exposed to moisture. The transportation, loading and storage of the carton from the conveyance between the packaging machine/packer unit and the retailer display are all sources for damage and moisture absorption.
The raw paper edges are a by-product of the composition of the carton blank. Generally, the carton blank is cut and scored from a sheet of coated fiberboard material. The coated fiberboard material is usually composed of three layers, and may have a barrier layer juxtaposed between fiberboard layers. The exposed surfaces of this sheet are coated with a polymer material such as polyethylene. However, the coating does not extend to the edges which are thus left uncoated, and partially unprotected at least to moisture and sensitive to damage. When the carton is erected and partially formed, these raw paper edges are most prevalent at the bottom of the carton. If moisture is absorbed into the raw paper edges, the water may be absorbed throughout the fiberboard interior layer, which due to its cellulose-like nature, has a strong affinity for liquids. This absorption of moisture may compromise the integrity of the carton thereby rendering it defective.
This problem has yet to be directly addressed by the packaging industry. However, inventions directed to resolving the stability of cartons have been disclosed in the prior art. Mills et al., U.S. Pat. Nos. 5,482,204, and 5,588,943, respectively for a Carton Bottom Sealer and Carton Bottom Sealing Dies disclose cartons having an embossed inverse pyramidal bottom which is directed to providing greater stability to the filled carton and to reduce bulging of the carton. It should be noted, as shown in FIGS. 8 and 9 of the Mills et al. Patents, that the end portions of the exposed raw paper edges of the bottom of the carton are not embossed, and therefore are susceptible to moisture absorption.
Fujikawa et al., U.S. Pat. No. 5,222,667, for a Container Made Of Paper-Base Laminate, similarly discloses a carton having an inverted V-shaped bottom to provide greater stability to the carton. As shown in FIG. 6 of the Fujikawa et al. Patent, the raw paper edge of panel 27 is not inverted and is susceptible to moisture absorption since the V-shaped inversion begins at the raw paper edge and since the inversion must be centered to provide stability to the carton.